Presenter Information

Event Website

http://www.nafew2009.org/

Start Date

23-6-2009 4:20 PM

End Date

23-6-2009 4:40 PM

Description

Waring and Pitman suggested that high growth efficiency (GE) (i.e. basal area increment/sapwood area - considered a measure of tree vigor) is related to the ability of lodgepole pine to defend against mountain pine beetles (Dendroctonus ponderosae Hopkins) (MPB). In this study we explore the relationship between GE, and other measures of vigor such as tree size, live crown ratio, growth increment, stem, foliage nutrients and root carbohydrate reserves. We then compare these measures of vigor with characteristics of tree defense such as density of resin ducts, monoterpenes and size of phloem lesions after inoculation with Grossmania clavigera (a blue stain fungus associated with MPB). In a field experiment we tested the suggested relationship between vigor and defense by thinning and fertilization in ten pure lodgepole pine stands in central Alberta. In the third summer after the fertilization and thinning treatment we inoculated trees with the blue stain fungus. The combination of fertilization and thinning increased GE and resin duct density but negatively impacted starch reserves. Lesion size increased with tree size in control plots, however, this relationship was lost when trees were fertilized and thinned. This suggests that treatments to increase growth rate also increased constitutive defenses in larger trees.

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Jun 23rd, 4:20 PMJun 23rd, 4:40 PM

Does the Relationship Between Tree Vigor and Defense Respond to Fertilization and Thinning?

Waring and Pitman suggested that high growth efficiency (GE) (i.e. basal area increment/sapwood area - considered a measure of tree vigor) is related to the ability of lodgepole pine to defend against mountain pine beetles (Dendroctonus ponderosae Hopkins) (MPB). In this study we explore the relationship between GE, and other measures of vigor such as tree size, live crown ratio, growth increment, stem, foliage nutrients and root carbohydrate reserves. We then compare these measures of vigor with characteristics of tree defense such as density of resin ducts, monoterpenes and size of phloem lesions after inoculation with Grossmania clavigera (a blue stain fungus associated with MPB). In a field experiment we tested the suggested relationship between vigor and defense by thinning and fertilization in ten pure lodgepole pine stands in central Alberta. In the third summer after the fertilization and thinning treatment we inoculated trees with the blue stain fungus. The combination of fertilization and thinning increased GE and resin duct density but negatively impacted starch reserves. Lesion size increased with tree size in control plots, however, this relationship was lost when trees were fertilized and thinned. This suggests that treatments to increase growth rate also increased constitutive defenses in larger trees.